Controlling parents at 20

I'm 20 years old and my parents forbid me from dating. Specifically from dating a (seasonal) co-worker.

For them to control my love life is one thing, but recently they have been attempting and controlling my career/job path by refusing me from auditioning for theme parks (I'm a performer).

When/ how can I tell my parents I need to be the author of my own life? I feel as if they put in too much pressure and perfection on my life for me to handle. On one hand, I live with them during the summer, but yet I'm an adult. It's a difficult time for me.

Advice?